title: Genetic variation in dopamine-related gene expression influences motor skill learning in mice.
abstract: Several neurodevelopmental disorders with a strong genetic basis, including attention-deficit/hyperactivity disorder, autism spectrum disorders and developmental coordination disorder, involve deficits in fine motor skills. This phenotype may depend on heritable variation in components of the dopamine (DA) system, which is known to play a critical role in motor skill learning. In this study, we took advantage of two inbred strains of mice (BALB/c and C57BL/6) that differ markedly in the number of midbrain DA neurons in order to investigate the influence of such naturally occurring genetic variation on the acquisition and performance of fine motor skills. Gene expression analysis of midbrain, frontal cortex and striatum showed significant differences in the expression of presynaptic and postsynaptic dopaminergic (DAergic) markers (e.g. tyrosine hydroxylase, DA transporter, DA D4 receptor, DA D5 receptor and DARPP-32) between these two strains. BALB/c mice had lower learning rate and performance scores in a complex skilled reaching task when compared with C57BL/6 mice. A negative correlation was found between the motor learning rate and level of DARPP-32 mRNA expression in the frontal cortex contralateral to the trained forelimb. The rate of motor learning was also negatively correlated with the levels of DARPP-32 and DA D1 receptor mRNAs in the striatum. Our results suggest that genetically driven variation in frontostriatal DAergic neurotransmission is a major contributor to individual differences in motor skill learning. Moreover, these findings implicate the D1R/cAMP/DARPP-32 signaling pathway in those neurodevelopmental disorders that are associated with fine motor skill deficits.
authors.affiliation: Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Y
authors.initials: Y
authors.lastname: Qian
authors.forename: M
authors.initials: M
authors.lastname: Chen
authors.forename: H
authors.initials: H
authors.lastname: Forssberg
authors.forename: R
authors.initials: R
authors.lastname: Diaz Heijtz
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism / Q000502:physiology; D004298:Dopamine / Q000378:metabolism*; D050483:Dopamine Plasma Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32 / Q000235:genetics / Q000378:metabolism; D059290:Dopaminergic Neurons / Q000378:metabolism / Q000502:physiology; D014644:Genetic Variation; D007858:Learning; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009048:Motor Skills; D050638:Receptors, Dopamine D4 / Q000235:genetics / Q000378:metabolism; D050641:Receptors, Dopamine D5 / Q000235:genetics / Q000378:metabolism; D013569:Synapses / Q000378:metabolism; D009435:Synaptic Transmission; D014158:Transcription, Genetic
chemical_list: D050483:Dopamine Plasma Membrane Transport Proteins; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; C497929:Ppp1r1b protein, mouse; D050638:Receptors, Dopamine D4; D050641:Receptors, Dopamine D5; D004298:Dopamine
keywords: DARPP-32; dopamine D1 receptor; inbred strains; motor coordination; skilled reaching task